about the
character of the community backed up by a concrete
existential witness, live in the classroom :) .
Thanks again to Chris, Gwern Branwen, _why (of TryRuby) and everyone
else for their efforts and interactions.
-- Fritz Ruehr
, these funds
have been used to purchase courtesy shirts for a few
Haskell luminaries, at the discretion of the store proprietor.
(Currently I think there are about $60 available.)
-- Fritz (Ruehr)
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merchandise page on CafePress! :)
-- Fritz Ruehr
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In lab the other day I was showing pattern bindings to a student and
broached a limiting case, one with no variables to be bound in the
pattern. I was surprised to find that Hugs crashed when I tried a
pattern binding at top level like this:
(2,[1,4],5) = (2,[1,4],5)
It also
, at 6:49 pm, Derek Elkins wrote:
Top-level bindings are irrefutable, so 2 = 3 is fine, if vacuous.
On Fri 4 Apr 08, at 6:53 pm, Ryan Ingram wrote:
On 4/4/08, Fritz Ruehr [EMAIL PROTECTED] wrote:
In fact, even this goes through without a hitch!
2 = 3
This is hilarious.
Maybe
Mathematical logic would be a good thing to study if you haven't
already, especially if you can take something as specific as
intuitionistic / constructive / substructural logic. The Curry-Howard
correspondence lurks underneath a lot of Haskell intuitions and
techniques.
-- Fritz
On
Once during a talk I noticed I was getting strange looks and realized
I was using the term string too freely with an audience of non-
technical people. About half of them were in a beginning linguistics
class and could at least handle trees later on (which terminology I
had thought in
For what it's worth, a handful of people who have ordered Haskell
merchandise from the CafePress store over the years have had
Haskell as a surname. I assume they look at the designs before they
buy, and I can't imagine what they think of some of them, but I guess
the allure of having your
I seem to recall that Aarne Ranta ran Hugs on a (Sharp) Zaurus PDA at
one of the ICFPs a few years back. Aha, here in fact is a picture of
his GF (Grammatical Framework), written in Haskell, running on a Zaurus:
http://www.cs.chalmers.se/~aarne/GF1/doc/zaurus2.jpg
There seem to be
I am wondering about the visibility of definitions in the Hugs
Prelude. More specifically, when I ask for info about the Eq class, I
see a lot of instances, including:
instance Eq Key
On the other hand, Key is not in scope:
Hugs :info Key
Unknown reference `Key'
I imagine this has to
According to the documentation for System.Random (see http://
haskell.org/ghc/docs/latest/html/libraries/base/System-Random.html):
In addition, read may be used to map an arbitrary string (not
necessarily one produced by show) onto a value of type StdGen. In
general, the read instance of
I think Pivotal (http://www.cs.kent.ac.uk/projects/pivotal/) has
the live update behavior of spreadsheets.
I haven't played with it yet, but I saw Keith Hanna show off his
earlier Vital system; it even updates backwards in some sense; see
the Direct manipulation section at his site
I suppose this might be a good time to announce the tentative availability of BLACK t-shirts in the "Haskell Hackers" design, which in fact features a "monster". (Note that I am only responsible for the composition of elements on the shirt: the monster drawing itself comes from a dingbat font.)The
On Jul 26, 2006, at 6:44 PM, Sebastian Sylvan wrote:
For example ...
if :: Bool - a - a - a
if True t _ = t
if False _ e = e
-- example usage
myAbs x = if (x 0) (negate x) x
I suppose there might also be a case for flipping the arguments about
like this:
if :: a - a - Bool - a
On Jul 11, 2006, at 8:27 AM, ihope wrote:
On 7/10/06, Fritz Ruehr [EMAIL PROTECTED] wrote:
Were you interested in seeing the function, you could do so, at
least
for finite, total functions (you can also enumerate them, compare them
for equality, etc.). See my haskell-cafe message at
http
On Jul 10, 2006, at 8:44 AM, Johan Grönqvist wrote:
deriving Show is impossible as Func is not instance of Show. Can I make it instance of Show? I just want to define something like
...
and I am not interested in actually displaying any information about the function, ...
Were you interested in
On Jun 27, 2006, at 10:35 AM, Brian Hulley wrote:
I suppose they are the exception that proves the rule... :-)
Seems like there's a real opportunity here for someone who works in the
area of inference systems for error handling ... .
(Hmmm, pun-potential may not be the best way to pick a
t sort of thing idly doodling on the back of a napkin while he chats on the phone with his other hand. My mistake. :)
--
>From the thread (quoting Tom Pledger quoting me):
Tom Pledger wrote:
K. Fritz Ruehr writes:
:
| But Jerzy Karczmarczuk enlightened me as to the full generality possibl
a, Bounded a, Enum b, Bounded b) = Enum (a,b) where ...
-- Fritz
On Apr 1, 2006, at 2:01 AM, Fritz Ruehr wrote:
You can use type classes to implement this for *finite* functions,
i.e., total functions over types which are Enum and Bounded (and
Show-able), using for example a tabular format
What is the easiest way to name a combination of type classes, i.e., to
abbreviate the fact that a certain type is an instance of several
classes simultaneously? I have a vague sense that this is do-able, but
that I am messing up by trying to use an empty class body as below.
So in the code
Anyone interested in program verification issues in a Haskell context
should check out the Programatica project:
http://www.cse.ogi.edu/PacSoft/projects/programatica/
(I'm not sure how recent changes at OGI/PacSoft may have affected the
on-going status of this project, but there is a
I was introducing a fresh set of students to lambda abstraction in Haskell yesterday and had the following inspiration about a possible alternative syntax. I didn't end up showing the idea to the students -- too confusing -- but I thought I would float it here, as long as nobody takes it too
On Feb 14, 2005, at 2:07 AM, Daniel Fischer wrote:
A question for the point-free society:
Is there any advantage of defining
(.) = (.) . (.)
rather than
f . g = \x y - f (g x y) -- or f $ g x y ?
Analogous question for (.) . (.) . (.) etc.
Well, from the fact that you even pose the question,
Hmm, Hugs gives me this:
(.) . (.) . (.) :: (a - b) - (c - d - e - a) - c - d - e - b
which I think is correct, if still not transparent in its meaning.
(ghci gives me a slightly re-named and explicitly quantified
variation).
Basically, the idea is that this sort of expression, with n
Well, I don't know about modern works which might appeal to knowledge
of FP languages, but there is a well-known, 2-volume work by Cajori:
Cajori, F., A History of Mathematical Notations, The Open Court
Publishing Company, Chicago, 1929 (Available from Dover).
I know it through Ken Iverson
Hi John,
I'm curious if you know what the requirements (memory, model, etc.) for
running Hugs on a Zaurus might be: I am not normally a PDA sort of
person, but a quick search indicates that Zauruses (Zauri?) are
available (used) for around US $30-50 (e.g., 2MB ZR 5800 through 64 MB
SL-5500).
, Inc. make no profit
on the merchandise we sell at cost through CafePress.
-- Fritz Ruehr
PS: There are also some Haskell-themed infant/toddler clothing items
that haven't made it onto the Haskell merchandise page yet, see
http://www.cafepress.com/HaskellBoys and
http://www.cafepress.com
Well, as far as that goes, we can shave off a little bit (around 7%)
this way:
combs = mapM (\k-[0..k])
(As a bonus, it's even a bit more cryptic/symbolic, in the fine
tradition of APL one-liner character-shavings.)
But who's counting? :) :) :)
-- Fritz Ruehr
On Aug 11, 2004, at 3:22 PM
a cut).
-- Fritz Ruehr
PS: there have been a couple of silent updates to the merchandise
available, including a frisbee and some baby clothes (links below). A
bigger crop of new products will appear in a few months (I have been
upgrading my systems during a sabbatical and need to re-install some
difficult.
-- Fritz Ruehr
Hi,
Hopefully this is a simple question. I am wanting to know good ways
of using ., the function composition operator, when dealing with
currying functions.
Suppose I have the following functions defined:
f :: Int - Int
f x = x*x
g :: Int - Int - Int
Palgrave Macmillan has recently published the above title and is
looking for ways to promote it. ...
Any clues as to when it will be more easily available in the USA?
-- Mark
If you mean physical perusal in a bookstore, I wouldn't know, but the book
can certainly be gotten by mail-order
he
use and evolution of Lisp, through the influence of programmers who
are especially fond of a certain style of programming. And I may have an
unrealistically tidy view of the design of languages like Haskell and ML,
never having sat on a design committee :) .
-- Fritz Ruehr
[EMAIL PROTECTED]
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